Mediating effects of rumination on insomnia in cancer survivors: Influences of cancer-related fatigue, fear of recurrence, and psychological distress

Background: While advancements in cancer treatments have improved survival rates, they also lead to adverse effects such as insomnia, which significantly impacts survivors' sleep quality. Objective: This study explores the influence of cancer-related fatigue (CRF), Fear of Cancer Recurrence (FCR), and psychological distress, with rumination serving as a mediating factor, on the insomnia experienced by cancer survivors. Methods: The study involved 220 cancer survivors attending Shohada-e-Tajrish Hospital's oncology center in Tehran, Iran. Participants were selected through convenience sampling and completed several questionnaires: the Insomnia Severity Index, Fear of Cancer Recurrence Inventory, Cancer Fatigue Scale, Kessler Psychological Distress Scale, and Rumination Response Scale. Results: The results showed that the tested model had a good fit, and the correlation matrix demonstrated significant positive correlations between CRF (0.46), FCR (0.15), psychological distress (0.55), and rumination (0.42) with insomnia in cancer survivors (p < 0.05). Notably, CRF (B = 0.356, p < 0.001) and psychological distress (B = 0.339, p < 0.001) affect insomnia both directly and indirectly through mediation by rumination, while the impact of FCR on insomnia was indirectly significant (B = 0.73, p < 0.05). Conclusion: The findings suggest that interventions focused on managing rumination could be potential targets to alleviate insomnia and improve the sleep quality of cancer survivors.